Redditor: What percentage of pregnancies where the mother has confirmed Zika result in microencephaly? -What are the other complications of Zika that have been shown or are hypothesised? -Of the babies that do not have microencephaly do we have any idea what percentage are likely to be effected by other complications? -Are babies being born to mother’s with confirmed Zika being enrolled in large long term prospective cohort studies in heavily effected parts of the world currently?

Dr Spong: CDC recently reported an update on Zika-associated birth defects among U.S. infants who were exposed while in the womb. (https://www.ncbi.nlm.nih.gov/pubmed/28384133) They found that Zika virus–associated birth defects were reported in 5% of the fetuses/infants from completed pregnancies with laboratory evidence of possible recent Zika virus infection (51/972 completed pregnancies). The proportion increased to 10% when restricted to pregnancies with laboratory-confirmed Zika virus infection (24/250 completed pregnancies). And for women with confirmed Zika virus infection in the first trimester of pregnancy, birth defects were reported in 15% of fetuses/infants.

There are scientific publications that estimate microcephaly risks for women exposed to Zika during their first trimester. However, the studies used statistical modeling that’s based on limited data, so we need studies that can provide actual data to refine the estimates. For instance, it will be important to include data from asymptomatic Zika infections.

Children born to Zika-infected mothers can experience severe complications, which collectively are called congenital Zika syndrome. Most people think of microcephaly, but that’s just one of many complications. Some conditions, such as growth restriction and arthrogryposis (joints that are permanently bent and do not straighten), are detectable via prenatal imaging or during postnatal exams, while others, such as brain abnormalities and hearing and vision loss, can be subtle and require additional tests. Children who appear physically normal at birth can have developmental delays or even develop microcephaly or other problems later in infancy. You can learn more about Zika’s effects on the developing brain in this infographic.

One of our funded studies, the Zika in Infants and Pregnancy (ZIP) Study, is following women and their infants, whether or not they have Zika infection or show symptoms. ZIP is a multi-country study that is enrolling pregnant women, ages 15 year and older, at nine sites in five countries: Puerto Rico, Brazil, Colombia, Guatemala, and Nicaragua. Participants are being followed through their pregnancies. Infants will be followed for at least one year after birth. This long-term study will evaluate the magnitude of health risks that Zika virus infection poses to pregnant women and their developing fetuses and infants. Enrollment is at a few thousand and counting. You can read more about the ZIP study and watch a video here: https://www.nichd.nih.gov/news/releases/Pages/zika_zip_06202016.aspx.

Redditor: Do you believe the Zika virus will be something that stays in our system permanently? Or is it like the common cold (and eventually goes away after a couple of weeks?) e.g. if a woman gets the virus, is she then in danger of birth defects for her children for the rest of her life? or only for a period of time?

Dr Spong: Right now, there is no evidence that prior Zika virus infection poses a risk to future pregnancies.

However, Zika can persist in bodily fluids. Studies are underway to find out how long Zika stays in the semen and vaginal fluids of people who have Zika, and how long it can be passed to sex partners.

Research supported by another NIH institute, the National Institute of Allergy and Infectious Diseases (NIAID), shows that protective immunity can develop in an animal model of Zika infection.

However, we don’t know how immunity develops in people. One of NIAID’s candidate Zika vaccines is in a phase 2/2b clinical study to gain safety and immune response data.

Redditor: Do you think the virus is on a spectrum? I’m not sure how to word it. Can some children carry worse cases than other children?

Dr Spong: Thanks for your thoughtful question! Children born to Zika-infected mothers can experience a range of complications, which collectively are called congenital zika syndrome. Researchers are trying to understand the full impact of Zika infection (i.e., what are all the complications?) and why some fetuses or infants develop some problems while others do not.

Most people think of microcephaly (small head), but that’s just one of many complications. Some conditions, such as growth restriction and arthrogryposis (joints that are permanently bent and do not straighten), are detectable via prenatal imaging or during postnatal exams, while others, such as brain abnormalities and hearing and vision loss, can be subtle and require additional tests. Children who appear physically normal at birth can have developmental delays or even develop microcephaly or other problems later in infancy. These are all long-term conditions that require medical treatments and therapy.

You can learn more about Zika’s effects on the developing brain in this infographic.

One of our funded studies, the Zika in Infants and Pregnancy (ZIP) Study, is following women and their infants, whether or not they have Zika infection or show symptoms. ZIP is a multi-country study that is enrolling pregnant women, ages 15 year and older, at nine sites in five countries: Puerto Rico, Brazil, Colombia, Guatemala, and Nicaragua. Participants are being followed through their pregnancies. Infants will be followed for at least one year after birth. This long-term study will evaluate the magnitude of health risks that Zika virus infection poses to pregnant women and their developing fetuses and infants. Enrollment is at a few thousand and counting. You can read more about the ZIP study and watch a video here: https://www.nichd.nih.gov/news/releases/Pages/zika_zip_06202016.aspx.

Redditor: How long should potential mothers wait after having been exposed to possible Zika carrying mosquitoes before attempting conception?

Dr Spong: CDC has guidelines for people who have traveled to an area with Zika and for people who live in an area with Zika. You can read their recommendations at: https://www.cdc.gov/zika/prevention/protect-yourself-during-sex.html. If you scroll down the CDC page, they offer specific guidance on how long to wait depending if one or both partners travelled.

For women who travel to an area of active Zika transmission she should wait at least 8 weeks after the last exposure before trying to get pregnant. For men who travel to an area of active Zika transmission they should wait at least 6 months after the last exposure before trying to get pregnant. https://www.cdc.gov/zika/pregnancy/women-and-their-partners.html

Redditor: Does Zika pose any risks or affect development if contracted by young children?

Dr Spong: Currently, CDC’s travel advisories are limited to pregnant women and couples trying to become pregnant. Based on research from CDC (https://www.cdc.gov/mmwr/volumes/65/wr/mm6539e2.htm?s_cid=mm6539e2), Zika infection in children is typically mild. In the study, only two children were hospitalized, and no deaths occurred. Serious complications of Zika virus disease, such as Guillain-Barré syndrome, were not reported for any children in the analysis – 129 (82%) children had rash, 87 (55%) fever, 45 (29%) conjunctivitis, and 44 (28%) arthralgia, or joint pain.

However, we do not have much information on the impact of Zika infection on a newborn or infant who was not exposed during pregnancy. We know that development continues beyond pregnancy, and the brain continues to develop well past the adolescent period. It is important to study Zika infection very early after delivery, to evaluate whether the impact of Zika is similar to an infection that occurs at the end of pregnancy.